Paragon simple mods

AbsolutCorrupt

New member
Hello all! First post here, seems like a great forum. I am ramping up to do a Paragon build and I was considering keeping some options available on the exterior. I see sometimes people replace the clipping dip switches with external switches, I may do that... but one I haven't seen (maybe I'm not searching correctly) is making the 100k/1k resistors in R3 and R17 switchable. This is a very simple option, and so unless I'm missing something, I'm surprised I haven't seen those brought to switches with the resistors in line on each throw and the pole returning to the board. I'm not saying I'd need to flip this while the circuit is hot, but is there any practical reason why I shouldn't do this? Or why one wouldn't?
I feel like with any gain/OD/Dist pedal, more selectable gain options, knobs, switches = more fun

Thanks!
 

Chuck D. Bones

Well-known member
I'm all for more knobs and switches, just check out my builds. Instead of switching R3 and R17, you can get the same effect by making R3 & R17 1K and changing the DRIVE pots to C250K (or even C500K!). If you don't plan on using the bottom end of the DRIVE control, then making R3 & R17 10K is probably about right because there will be little difference between 1K and 10K.

As for switching the diodes, the sky is the limit. Consider ON-OFF-ON switches and adding alternate diodes such as LEDs, Schottky or Germanium. Maybe some asymmetric clipping.
 

AbsolutCorrupt

New member
I'm all for more knobs and switches, just check out my builds. Instead of switching R3 and R17, you can get the same effect by making R3 & R17 1K and changing the DRIVE pots to C250K (or even C500K!). If you don't plan on using the bottom end of the DRIVE control, then making R3 & R17 10K is probably about right because there will be little difference between 1K and 10K.

As for switching the diodes, the sky is the limit. Consider ON-OFF-ON switches and adding alternate diodes such as LEDs, Schottky or Germanium. Maybe some asymmetric clipping.
Ahhh, ok yes I see that on the drive pots. Simple enough. I think I want to keep the 1K so I don’t lose the low gain option, but changing the pots to C250K Gives me a larger sweep on gain. I like that. Thanks.

Can you link to something or briefly explain the connection of the on-off-on switches? From the schematic I see it as I would need 4 separate switches for all functionality...?
 

Chuck D. Bones

Well-known member
Bumping the pot up to 250K gets you the low gain option without resorting to 1K for R3 and R17, but do what you like.
 

AbsolutCorrupt

New member
Ah, I think I see.
Looking at it as a divider circuit with an adjustable upper half: So original low gain specs are 100K:1K ratio on the divider circuit there, with overall impedance of 101K... but when we up it to 100K:100K with a total of 200k for high gain per specs, we could instead use a 250k pot so it has a wider sweep over a larger percentage of the divider. Is this correct? And then the R3/17 resistors are more of just a pad on the low end of the pot to keep it from going to “zero”?
If so, is there any harm in just putting a 250k or 500k pot in there and bypassing the R3/17 resistors entirely? This is more of a theoretical, I’m just wondering what harm it would do other than allowing the adjustment of the gain so low it was pointless.
Really appreciate your help.
 

Chuck D. Bones

Well-known member
You have it right.
R13 & R17 are only there to set a lower bound on the DRIVE control. The circuit will work fine with R3 and/or R17 jumpered. In the extreme case where the resistance between pins 1 and 2 on IC1 or IC2 goes to zero, the first stage becomes a unity-gain buffer and the tone shaping network between pin 2 and ground has no effect.
 

AbsolutCorrupt

New member
Hey, one more question about those drive pots, you mentioned C taper, but the build spec is B for the drive pots. I realize that it will still give me the range, it is just the taper profile... but do you recommend C for this application in particular?
 

Chuck D. Bones

Well-known member
I recommend C taper when the circuit is highly sensitive to pot position at the clockwise end of rotation. That is the case here because the total pot resistance is more than 10x R6 (or R20). The gain of channel 1's 2nd stage is R7 / (Rdrive + R6), where Rdrive is the resistance between pins 2 & 3 of the DRIVE pot. The gain goes up as Rdrive goes down.
 
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Feral Feline

Active member
I'm a big fan of adding a 2nd "Channel" or option to a build by having one control-parameter receive two different pots on a stomper (or toggle switch if you prefer).

For example you could have two 250k pots for Gain on a fuzz pedal, switchable by a stomper. Set one pot for low gain, the other for high gain and let the master volume keep heads from blowing up.

You could have two different delay settings, or tremolo speeds or...
 

Barry

Well-known member
Let me see if I understand this @Chuck D. Bones , if I bump drive pots to 250K and leave R3 and R17 at 1K, I pretty much have the high gain and low gain options?
 
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